You can get better lighting from full spectrum bulbs but unless you have live plants you may be growing tons of algae if you increase your light.
The standard 55 comes with two 20 inch bulbs I think...Normal Output flourescents (at least mine did) and it had a total of 30 watts over the tank. Not much light, pretty dim actually so I get what you are trying to do. If you are NOT wanting a planted tank but just wanting a brighter tank you can get new lights but keep it under 1 watt per gallon. Otherwise...if you love a bright tank then look into planting it, a 55 is a great size for planting all kinds of stuff.
You could get a fixture that is 2 x65w power compact and it will give you about 1.7 wpg which is a good low light level where you can keep it low tech, not dosing much fert, using root tabs and no CO2 and you can keep a variety of crypts, annubias, mosses, amazon swords, hygro, and it makes a nice bright jungle of a tank.
Whatever you decided good luck.
Some more specific questions will lead to some more helpful answers as well.
Good luck with your tank...would love to see pics.